Safety stop device for drop hammers or the like



Sept 7, 1954 c. PRlEsML-:YER

SAFETY STOP DEVICE FOR DROP HAMMERS OR THE LIKE Filed Sept. 16, 1,952

Patented Sept. 7, 1954 SAFETY STOP DEVICE FOR DROP HAMMERS OR THE LIKE Charles Priesmeyer, Park Ridge, Ill., assigner to Meyer & Wenthe, Inc., a corporation of Illinois Application September 16, 1952, Serial No. 309,810

(Cl. '7S- 25) Claims.

This invention relates to safety stop device for a drop hammer or the like.

It is well known that drop hammers that fall by the elfect of gravity and which are elevated by leather belts or other iiexible straps are in danger of falling accidentally by reason of broken straps or other failure of the lifting expedients, and, in such event, are extremely hazardous to the safety of the operator whose hands would be seriously injured if they be in the path of the hammer at the time of such failure.

While it is not new generally to provide a safety stop to limit accidental downward movement of the hammer head, such devices heretofore suggested have been unsatisfactory, due in large measure to the fact that the stop devices themselves have been subject to failure or breakage for one reason or another and principally because they have been arranged to take the full force of the blow of the accidentally falling hammer.

The present invention is directed to the solution of the problem of providing a safety stop device which does not take the full force of the blow of the accidentally falling hammer but rather distributes the force in part to the hammer frame or guide-way upright so as to reduce the blow on the safety device and greatly minimize or eliminate danger of its failure or breakage.

In carrying out this aim, the present invention employs the principle of the wedge, so that, when the stop piece of the safety device is struck by the hammer, the blow is taken by the stop piece on a slanting or tapered surface thereof, thus not only making the blow a glancing one rather than a direct shearing action but at the same time tending to give the hammer-head a component of force in a lateral direction, or direction transverse to the guide-ways, and thus bringing the guide-way uprights into play as a stop element and materially reducing the stress on the safety device.

The invention will be understood and the foregoing and other objects thereof will be apparent from the following detailed description, taken together with the accompanying drawings, of an illustrative embodiment of the invention, and in which drawings:

Figure 1 is a partial front elevation of a conventional drop hammer apparatus with which the invention is shown associated;

Figure 2 is a fragmentary side view of parts shown in Fig. 1; and

Figure 3 is a partial cross-section taken on the line 3 3 of Fig. 1.

Referring in detail to the illustrative construction shown in the drawings, the parts numbered II and I2 may represent vertical guide-way uprights for a drop hammer or press, and, in this instance, accommodating a hammer-head I3 having on its lower face a die I4 adapted to cooperate with a die block or anvil l5 mounted on a base I6 from which the guide-ways II and I2 upstand. It will be understood that the hammer-head I3 has a tongue-and-groove relationship as at Il and I8 with the guide-way uprights between which it is permitted to fall under the influence of gravity to forge or form an article (which need not be here described) between the dies I4 and I5. The hammer-head may be elevated to its position as shown in full lines in Fig; 1 by mechanism forming no part of the present invention, and which need not be here described, except to point out that customarily the hammer-head is raised and held releasably in this elevated position by a strap I9 commonly made of leather which is passed through a bail 20 on the hammer-head and riveted to itself as at 2l. K

It will also be understood that to guard against the hands of the operator being in the path of the hammer when it is falling, release mechanism for the hammer-head is controlled by a plurality of levers or the like, both of which must be grasped by the operator, one by each hand, before the hammer head is permitted to fall, and, in this instance, two such levers 22 and 23 are indicated. For example, unless both of the levers 22 and 23 are elevated on their pivots 24 and 25 respectively the hammer-head is not released to fall. When both are raised simultaneously, through expedients which Vneed not be here gone into, the hammer-head is permitted to fall. The levers 22 and 23 may have handle knobs 2t and 2l respectively.

Turning now to the present invention and in adapting it to practice as here shown, bolts or studs 28 and 23 may be employed advantageously to mount, on one of the guide-way uprights and in this instance the upright I2, the stop device of the present invention, which includes a Ihousing 33 that is desirably set into a recess 3l in the guide-way upright I2, the housing having bolt-holes 32 and 33 at its upper and lower end respectively for passage of the studs 28 and 29 therethrough, thus Xing the housing rmly in position on the guide-way upright I2. The stop device may be located at any suitable and convenient distance above the anvil I5.

The housing 30 encloses operating parts for the safety stop device of the present invention, and, following the latter, has a recess 34 in which plays the stop piece 35 that, as here shown, is pivoted at 36 on the stud 28 at the upper end of the housing and depends therefrom to swing at its lower end into and out of the recess 34, out of the path or into the path, as the case may be, of the hammer-head I3. The lower end of the stop piece 35 is preferably slanted or decreasingly tapered, and projects, when in the path of the hammer head, through a slot 31 in the inner edge of the housing facing the space between the guide-ways II and I2. An expansion coil spring 38, anchored at one end on a screw 39 in the housing spring recess 40 and hooked at its other end to a perforated lug 4I on the lower end of the stop piece, normally acts to retract the stop piece into the housing and out of the path of the hammer-head.

A cover plate 42 (shown in Fig. 2 but omitted in Figs. 1 and 3) may be employed, located on pegs 43 and secured to the housing as by screws 44 entering tapped holes 44a to retain the stop piece 35 and other parts in position as presently described.

Further in accordance with the present invention, before the cover plate is placed on the housing, means are provided for moving the sto'p piece into the path of the hammer-head, and for blocking the stop piece in such position, to limit downward movement of the hammer-head to a point short of (i. e. above) the anvil I5. In this instance such means are here shown in the form of a trip member 45 which is also pivoted in the housingr30 on a trunnion 41, the inner end of which carries an eccentric 48 xed thereon to play in a recess 49 in the housing opening into the recess 34. The eccentric is located in this position before the cover plate is pressed on the housing, and thereafter the arm element 50 of the trip member 45 is xed in position on the outer end of the trunnion 41. The arm element 50 is rigid with the trunnion 41 as at 46.

The double ended trip arm element 50 has one end or arm I and the other end or arm 51a. The arm 5I is in the shape of a triangular frame, one side 52 of which is somewhat arcuate so that its lower edge 53 provides a cam surface for cooperation with an auxiliary lever 54 that is pivoted at 55 on the guide-way upright I2 and is connected by link 56 with release lever 23, as at 56a on the auxiliary lever 54 and 56h on the release lever 23, the usual articulated yokes 55C being used for this purpose. The auxiliary lever 54 is arranged to move, under the influence of release lever 23, in the 4path of the trip arm 5I. The other end 5Ia of the double ended trip arm extends in the opposite direction from the end 5I, and, when the trip arm is in the position shown in dotted lines in Fig, l, the arm 5Ia extends into the path of a reset finger 51 hinged as at 58 on a projection 59 extending forwardly of the hammer head I3.

Reset nger 51 is normally retracted to hori- Zontal position as shown in full lines in Fig. 1 in any suitable manner, such as by an expansion coil spring 60 which may be anchored at one end as at 8l to the projection 55 and at the other end as at 62 to the finger 51. At its outer end the nger 51 carries an anti-friction roller 63. The tip of the trip arm 5Ia is beveled as at 64 for cooperation with the anti-friction roller 83.

Operation of the safety device is as follows:

When the parts are in the position shown in full lines in Fig. l, with the hammer-head elevated and the release levers 22 and 23 unactuated and in depressed position, the trip arm 50 may be initially manually set so that its triangular end 5I is depressed. Rotation of the trip arm in this direction rotates the eccentric 48 clockwise so that the latter moves the lower end 35a of the stop piece 35 (expanding the coil spring 38) outwardly of the housing and into the path of the hammer-head I3. A cam surface 65 on the eccentric 48, engaging flatly against the inner edge of the stop piece 35, fixes this relationship until the trip arm is rotated in the opposite direction.

When the parts are thus disposed, downward movement of the hammer-head I3 below the stop piece is prevented. Should breakage of the belt I9 or other failure of the elevating mechanism occur, and the hammer-head I3 drop accidentally, the lower corner 66 of the hammer-head will be engaged `by the tapered or slanting edge 61 of the stop piece 35, and, because of this taper or slant, the hammer-head will tend to ride down further to cause the stop piece to be wedged between the hammer-head and the eccentric 48. Because of the flat surface 65 on the eccentric, this wedging action will not tend to rotate the trip arm, since the eccentric is aligned with its at surface normal to a radius from its pivot point substantially coincident with the direction of force of the hammer-head on the stop piece, and, in turn, of the stop piece on the eccentric, the latter thus blocking any tendency of the stop piece under the influence of the weight and velocity of the hammer-head to be forced back into the housing.

Advantageously not all of the force of the accidentally falling hammer-head will be transmitted to the eccentric 48, since, by reason of the wedging action of the stop piece already referred to, the hammer-head, as Well as the stop piece, will be subjected to a lateral component of force which will tend to push the hammer-head against the opposite guide-way upright II. Thus the tapered or slanting surface 61 of the stop piece which the hammer-head engages, and the resulting wedging effect of the stop piece, serve the novel and useful function and purpose of relieving the safety device parts of the full force of the blow of the accidentally falling hammer-head and distributing this force not only to the guideway upright I2, which, in this instance carries the safety stop device parts, but also to the opposite guide-way upright II, so as to dissipate the kinetic energy of the falling hammer-head and minimize danger of breakage or failure of the safety stop device parts and particularly of the stop piece itself. This safeguard is further enhanced by reason of the fact that, as so constructed and arranged, the stop piece is not at any time subjected to any substantial shearing action but rather to a wedging action. The accidentally falling hammer-head would thus be stopped well short of the anvil I5, so that the hands of the operator would not be injured should they be resting on the anvil.

In order to permit the usual and normal operation of the drop hammer, when the hands of the operator are in a safe position for operation, as when one hand of the operator is grasping the release lever 22 and the other hand the release lever 23, and these lever are lifted for the release of the hammer-head I3, the lever 23 raises the auxiliary lever 54, and the latter in turn raises the arm end 5I of the trip arm 50, to the dotted line position in Fig. l. In doing this the auxiliary lever 54 slides along the arcuate cam surface 53 of the trip arm 5I. This rotates the eccentric 48 vcounterclockwise and permits the lower end 35a of the stop piece 35 to fall back into the housing and specifically into the recess 34 in the housing. The stop piece is urged in this direction by the resilience of the spring 38. The hammerhead i3 may thereupon fall to its full extent onto the anvil l5 for operational purposes, this fall, of course, occurring almost instantaneously with the action of the operator in raising the release levers 22 and 23.

During this normal drop of the hammer-head, the reset nger 5l on the hammer-head rides over the beveled end of the trip arm Sla, as indicated in dotted lines in Fig. 1, the spring 60 yielding for this purpose, so that the safety device is at this time inoperative. As soon of the hammer-head drops past the safety device, the reset nger l returns to horizontal position under the iniiuence of the spring B0, being limited from further downward movement by block 59.

After the operational drop of the hammer-head, it may be again elevated to its full line position in Fig. 1 by mechanism not here concerned with and which therefore need not be described. In the elevation of the hammer-head, however, it is desirable to reset the safety device, and means in the contemplation of the present invention, the parts of which have already been described, are provided for this resetting purpose, such means being here illustrated by the reset finger 5l to cooperate with the trip arm 51a, that is, the other end of the trip arm element 50 opposite from the end 5l.

When the hammer-head is raised from its dropped position for operational purposes, the reset finger 5l being now in horizontal position engages the under-edge of the trip arm lila and rotates the trip arm 50 into the full line position shown in Fig. 1 as the hammer-head moves upwardly past the safety device, the cycle being thereupon repeated and the eccentric 48 moving the lower end of the stop piece out of the casing and again into the path of the hammer-head, where it is maintained by the blocking action of the eccentric with its cam surface 65 until the auxiliary lever 54 is raised another time by the action of the operator in raising the release levers 22 and 23.

The invention is not intended to be limited to details of construction shown for purposes of illustration, and such changes may be made as fall within the scope of the appended claims without departing therefrom.

What is here claimed is:

1. n a device of the class described, the combination with a vertically reciprocable hammerhead and guide-way elements therefor and a lever for activating release mechanism permitting the hammer-head to drop, of a safety stop device mounted on one of said guide-way elements for limiting downward movement of the hammerhead, said stop device comprising a pivoted wedge piece, a pivoted block member including a pivoted combined eccentric and trip arm for moving the wedge piece, and means including said release lever for actuating said trip arm to move the eccentric out of the way of the wedge piece thereby permitting the wedge piece to move out of the way of the hammer-head.

2. A safety stop device for drop hammers or the like, comprising a casing, an elongated stop piece pivoted at its upper end in said casing to swing therein into and out of the casing at its lower end, an eccentric also pivoted in said casing below the pivot for the stop piece, said eccentric being rotatable into and out of blocking relations with the stop piece, and a trip arm rigid with and for rotating the eccentric into and out of said blocking position.

3. The structure of claim 2 wherein the trip arm is outside the casing and has a trunnion part inside the casing carrying the eccentric.

4. The structure of claim 2 wherein the stop piece is spring retracted into the casing.

5. The structure of claim 2 wherein the trip arm carries a cam surface for engagement with a hammer head release lever to cause actuation of the trip arm to permit movement of the eccentric into the casing.

6. The structure of claim 2 wherein the trip arm carries an end for engagement with a reset finger on the hammer-head for rotating the eccentric to move the stop piece out of the casing.

7. A safety stop device for drop hammers or the like, comprising an elongated wedge-shape stop piece pivoted at its upper end to swing into and out of the path of the hammer-head, said stop piece being decreasingly tapered toward its lower end, an eccentric pivoted adjacent the lower end of the stop piece and rotatable into position to swing said stop piece into the path of the hammer, a cam surface on said eccentric, said eccentric being then aligned with said cam surface normal to a radius from its pivot passing through the direction of force of the stop piece on the eccentric, a double ended trip arm rigid with the eccentric spaced laterally thereof having one end engageable by a release lever for the hammer head release mechanism to rotate the eccentric out of blocking position with the stop piece to permit the hammer to drop past the stop piece, and having another end engageable by a reset finger on the hammer-head for rotating the eccentric to move the stop piece back into the path of the hammer-head when the latter is elevated.

8. The structure of claim 7 wherein one end of the trip arm has a cam surface thereon for engagement with a member actuated by said release lever.

9. The structure of claim 7 wherein the trip arm end engageable by the reset finger is beveled to cause the reset finger to ride thereover in downward movement of the hammer-head.

10. In a safety stop device of the class described, the combination with a vertically reciprocable hammer-head and drop guide-way elements therefor, of a vertically elongated stop piece pivoted adjacent its upper end on one of said guide-way elements and swingable at its lower end into and out of the path of the hammer-head, a block member engageable with one edge of the stop piece and movable to swing the stop piece into the path of the hammer-head to place the opposite edge of the stop piece slantingly in the path of the hammer-head, whereby the hammer head engages said opposite edge of the stop piece and said stop piece is wedged between the hammer-head and the block member to prevent further downward movement of the hammer head, and means for moving the block member to permit the stop piece to swing out of the path of the hammer-head to permit further downward movement of the hammer-head.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 41,775 Hotchkiss Mar. 1, 1861 823,480 McLeod June 12, 1906 1,242,052 Scott et al. Oct. 2, 1917 1,531,491 Macready et al Mar. 31, 1925' 1,604,089 Topf-l Oct. 19, 1926 1,606,717 Murray Nov. 3, 1926 y2,220,036 Fitzgerald et al. Oct. 29, 1940 

